TNO2024

In addition to its close flybys of the Pluto system in 2015 and classical TNO Arrokoth in 2019, NASA's New Horizons Mission has observed over 35 other TNOs and dwarf planets as unresolved point sources at viewing geometries unattainable from Earth or Earth-orbit. From these unique vantage points, observations of TNOs acquired by the spacecraft's LOng Range Reconnaissance Imager (LORRI) have been used to characterize their surface microphysical properties, shapes, rotation poles and periods, as well as search for close companions. New Horizons has already discovered one tight binary TNO and another candidate binary, owing to its slow (> 40 hr) rotation. It also found that larger TNOs with highly volatile ices on their surfaces appear brighter at high Sun-TNO-observer (or solar phase) angles than the smaller TNOs with Arrokoth-like surface compositions. The smaller TNOs also appear to have flattened shapes, like Arrokoth, implying that these shapes represent typical end states for planetesimal formation. New Horizons continues to observe dwarf planets and TNOs using small amounts of its remaining fuel. Since the spacecraft has left the densely populated “classical” Kuiper Belt, upcoming TNO targets tend to be members of more distant populations in the scattered disk, some with apoapses that extend beyond the heliopause. The New Horizons Team continues to search for more TNOs for LORRI to observe, either as close or distant flyby targets, using primarily the Subaru Telescope's Hyper SuprimeCam. Hundreds of new TNOs have been discovered by these search efforts and reported to the Minor Planet Center (MPC). To date, New Horizons LORRI has observed TNOs from all dynamical classes: classical, resonant, and scattered disk objects as well as Centaurs and large TNOs. This presentation will summarize the results from TNO observations from New Horizons.